5-6 Change 3
Units will use the procedures listed below to obtain a proper fit with CEP and MBU-
5-8. CEP Fitting Techniques.
Proper fitting of the CEP is critical to attain optimum performance, as with any other piece of life support
equipment. While the techniques are not complicated, they must be complied with or, otherwise, hearing
protection and comfort may suffer. The CEP unit is composed of two parts: screw-on foam tips (soft), and
the CEP (two earplug transducers that are encased and connected by thin wires to an SMB connector). The
CEP wires have two different lengths. The CEP with the short length wire is for the right ear and the long wire
is for the left ear.
It is imperative that each crewmember is familiar with the donning, fitting, care, and
operation of the CEP system used in the aircraft. Failure to complete the following
procedures could result in personal injury to the crewmember.
a. The following procedures should provide a CEP fit that will yield optimum performance and best
overall comfort when wearing a helmet in combination with the CEP.
The CEP foam tips are available in three sizes: standard, short, and slim. Past studies
have shown that about 70% of the aviators use the standard size foam tips.
1. Attach a foam tip to each CEP transducer. Approximately one complete revolution of the
foam tip (right-hand thread) is all that is required. The rigid inner portion of the foam tips is
designed to fit into the recessed area around the base of the plastic threaded tip of the
2. Roll the foam tip and CEP, as one unit, between your thumb and first two fingers down to a
small diameter (just like the standard yellow foam earplug). Holding the CEP in one hand
and rotating the foam tip with the other hand may unscrew the foam tip from the earplug.
Never force or shove the foam tip into the ear canal. Always compress the foam tip
before inserting. Forcing the uncompressed foam tip into the ear will only pull the foam
portion away, exposing the hard plastic insert. The exposed plastic insert may cause
some pain or discomfort if it touches the ear canal.
3. While holding the CEP housing and wire with thumb and index finger, insert the
compressed foam tip into the ear canal until the transducer body is inside the external ear.
Position the transducer housing during the insertion so the wire exits through the tragus
"notch" of the ear. Helpful hint: Lift the top of your ear up and out to the side with your free
hand to straighten the ear canal.
4. Confirm proper fit by placing cupped hands over both ears and slowly moving back and
forth away from the ears. If there is no noticeable difference in hearing, then a proper seal
has been obtained for optimum sound attenuation. If not, select a different size foam tip
and repeat the process.